The present invention relates generally to displays. In particular, the present invention relates to electronic displays that can be used to view video from a video source, such as a surgical video microscope or a live camera feed of a patient during medical surgery. The present invention has particular application in viewing video of hard to view locations of a patient's body for dental, ophthalmic, oral, and endoscopic surgery.
In medicine and other fields, there is a need to view an object with a magnification and without magnification. There is particularly a need to have this capability concurrently in an ergonomic fashion. In the medical field, magnifying loupes, microscopes, digital microscopes, head mounted prisms and head mounted cameras have all been attempted in the prior art to address these issues.
In the medical field, camera and video displays have been employed by doctors to permit magnified and normal view of a patient. These devices are commonly used to display video from a video source, such as a live camera or playback media, such as DVD, videotape or computer video card output. A common video display is a computer monitor that can be a of a cathode-ray, LCD or plasma type, for example. Such a display is placed proximal to the user who desires to view the video content. In the case of a computing environment, the monitor is typically placed in front of the user and in behind the keyboard for ergonomic comfort and health reasons. In this environment, this fixed computer monitor enables the user to easily type on the keyboard and see what they are typing without large amount of head movement.
However, this arrangement is not suitable for viewing all types of video content. In the medical field, video cameras have played an important role in medicine to facilitate surgery, for example. More specifically, a high-powered camera can be placed very close to the part of the body being treated to visually aid the doctor during surgery and such treatment. It is currently well known to display such video content on a computer monitor that is close to the patient and the doctor so that the doctor can look back and forth at the video display and the patient. Depending on the surgery, the doctor may look more or less at the computer monitor that displays the video content from the camera. Due to the size and configuration of computer monitors, they can be placed only so close the patient without disrupting the surgery and interfering with the doctor and staff.
As a result, computer display devices in the surgical theatre require the doctor to frequently look away from the patient. The doctor must look down to view the patient in a normal mode and also must look up and away at the display device to view a video display, which, for example, is of a magnified view. This prior art arrangement, where the doctor is operating on a patient with their head posture compromised causes injuries, and the constant change of focal length is both disorienting and fatiguing.
There have been attempts in the prior art to provide a heads-up display, HMD, such as for use in the computer gaming industries. However, these heads-up displays are designed and configured so that the user's entire field of view is taken up by the video displays. This arrangement is meant to enhance a “virtual reality” view of the video content. This configuration is not suitable for use in a medical surgery environment because it requires the doctor to frequently put on and take off the heads-up display whenever they would like to switch from a normal view to video view or vice versa, and it disrupts the ability to function physically in the operating field, such has in the exchange of instruments.
Prior art also includes through the lens projection systems, which allow for the view of the direct field and the enhanced or data view. These through the lens or semi-transparent displays are most frequently, and appropriately, utilized in aviation, transportation and military applications. These users often require very rapid response to low resolution graphics. For example, an attack helicopter pilot may see a targeting curser or warning icon on their display. However, this obstruction of the normal view is unacceptable in surgery, where each view, magnified or not, must be of an extremely high level of acuity. The medical practictioner is generally not subject to the critical reaction times frequently encountered by military display users but is acutely in need of visually accurate, precise images.
In Human Factors, (Vol. 49, No 6, December 2007, pp. 1083-1096. DOI 10.1518/001872007X249947, Human Factors and Ergonomics Society.), a comprehensive review and analysis is provided of much of the published literature on the enduring problem of binocular rivalry that is relevant to the design and use of monocular and binocular head-worn displays (HWDs). These authors utilized a large body of scientific publications dealing with opaque and semi-transparent monocular and binocular head mounted display devices employed in a wide variety of experimental and field applications. Their belief is that the negative factors associated with current head mounted display devices have significantly limited their widespread acceptance and application.
When two eyes receive different stimulation on corresponding retinal areas, which precludes binocular fusion, a condition exists for creating a phenomenon known as binocular rivalry. Binocular rivalry refers to a state of competition between the eyes, such that one eye inhibits the visual processing of the other eye. The visibility of the images in the two eyes fluctuates, with one eye's view becoming visible while portions of the other eye's view are rendered invisible and suppressed, which reverses over time, causing perceptual confusion.
During binocular rivalry, portions of stimulation in one eye fail to gain access to higher visual processing stages or conscious awareness. During suppression, there is a general loss of sensitivity for all classes of stimuli that fall within the suppressed area of the retina. The loss of sensitivity can impair the ability of observers to visually guide attention to targets in the visual field.
Binocular rivalry is provoked by interocular differences in many kinds of image characteristics, such as contrast polarity, size, hue and motion velocity. These interocular differences are present in all, prior art, head mounted display devices, to a greater or lesser degree. See Blake, R., A Neural Theory of Binocular Rivalry, Psychological Review, 96, 145-167 (1989); Breese, B., On inhibition Psychological Monographs, 3, 1-65(1899); Howard, I., Seeing in depth: Vol. 1. Basic Mechanisms, New York: I. Porteous (2002); Howard, I. and Rogers, B., Binocular vision and stereopsis, New York: Oxford University Press (1995), and Levelt, W., On binocular rivalry, Soesterberg, Netherlands: Institute for Perception, RVO-TNO (1965).
Additionally, in the prior art, monocular and binocular head mounted display devices often cause numerous and similar negative effects on the user. For example, Wenzal et al., Assessment of the virtual environment safe-for-maintenance trainer, Mesa, Ariz., Air Force Research Laboratory (2002) found that aircraft maintenance workers reported problems such as eyestrain, headache, nausea and dizziness when a HMD was use. In a study by Behar et al., Visual survey of Apache aviators, (VISAA), Fort Rucker, Ala.: U.S. Army Aeromedical Research Laboratory (1990), a large number of helicopter pilots reported at least one visual complaint, such as visual discomfort, headache, blurred or double vision associated with flying an aircraft with an integrated helmet and display sighting system, a monocular transparent head mounted display device. Moreover, Rash et al., Human factors and safety considerations of night vision systems flight using thermal imaging systems, Proceedings of SPIE: Helmet-Mounted Displays II, 1290, 142-164, (1990) reported difficulty making the necessary attention switches between the eyes.
Therefore, there is a need for a multi-view system that is ergonomic, provides good head posture for the user and allows an unrestricted range of practitioner location. There is a need for a system where the user has a gaze selected video (e.g. magnified) view and a normal view available at all times with ergonomically correct head posture and correct optical/visual characteristic balance.